21418320 has 320 divisors, whose sum is σ = 88565760. Its totient is φ = 4147200.

The previous prime is 21418261. The next prime is 21418333. The reversal of 21418320 is 2381412.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 351090 + ... + 351150.

It is an arithmetic number, because the mean of its divisors is an integer number (276768).

Almost surely, 2^21418320 is an apocalyptic number.

21418320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21418320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44282880).

21418320 is an abundant number, since it is smaller than the sum of its proper divisors (67147440).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21418320 is a wasteful number, since it uses less digits than its factorization.

21418320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114 (or 108 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21418320 is about 4627.9930855610. The cubic root of 21418320 is about 277.7123121577.

Adding to 21418320 its reverse (2381412), we get a palindrome (23799732).

The spelling of 21418320 in words is "twenty-one million, four hundred eighteen thousand, three hundred twenty".